The present invention relates to a radiation source delivery wire for use in radiation therapy, mainly, in a cavity in the living body such as the blood vessel and a catheter assembly for radiation therapy, provided with the same.
Radiation therapy is a medical treatment by applying radiation source to a lesion tissue or the like. Recently, to intensify its treatment effect while reducing a side effect, a method has been employed in which a radiation source is placed just in the vicinity of the morbid tissue. For example, the radiation therapy is carried out to prevent a restenosis after percutaneous transluminal coronary angioplasty (PTCA) is carried out for coronary artery stenosis. In the radiation therapy, mainly a catheter or wire is used as a means for delivering the radiation source.
The radiation therapy includes, for example, inserting a catheter into a cavity of a patient, dwelling a distal end thereof in the vicinity of a target tissue, sending a radiation source delivery wire into the catheter with a predetermined method to position the radiation source near a target portion and dwelling it in the living body for a predetermined time so as to apply the radiation.
U.S. Pat. No. 5,728,042 discloses an example of the radiation therapy wire. It includes a core wire, wire coil (radiation source) made of radioactive substance. wound up around the core wire and radiopaque coils provided on the distal and proximal ends of the radiation source. Because this radiation therapy wire has radiopaque coils, a position of the radiation source can be detected. However, because the radiation source is composed of wire coil made of radioactive material, a size of the wire is relatively large and smoothness of the surface thereof is lost, so that when inserted into or removed from the catheter or lumen, the catheter or tissue may be damaged. A more important problem is that the flexibility of the entire radiation therapy wire is insufficient so that it is difficult to ensure the operability and safety of the catheter.
When the target tissue is located in a tortuous cavity or at a terminal of a branched cavity, if the flexibility of the wire for delivering the radiation source to the target portion is insufficient, operation of the wire and positioning of the radiation source become difficult.
Accordingly, it is an object of the present invention to provide a radiation source delivery wire wherein flexibility of a distal end portion thereof is improved and operability and safety can be secured when inserted into a cavity of a living body even if a target tissue is located in a tortuous cavity or at a terminal of a branched cavity, as well as a catheter assembly for radiation therapy provided with such a radiation source delivery wire.
Another object of the present invention is to provide a radiation source delivery wire whose radiation source position can be identified accurately so as to appropriately apply the radiation to the target tissue so that a bad influence upon the living body can be suppressed, thereby improving a treatment effect, as well as a catheter assembly for radiation therapy, provided with such a radiation source delivery wire.
To achieve the above objects, the present invention provides a radiation source delivery wire comprising: a flexible operating wire member; and an irradiation member including a radiation source for applying radiation to a target portion in a cavity of a living body, wherein the irradiation member including the radiation source is so constructed as to be flexibly bendable, and a distal end portion of the operating wire member constitutes a narrowing portion which gradually narrows toward its distal end.
Further, the present invention provides a radiation source delivery wire comprising: a flexible operating wire member; an irradiation member having a radiation source comprising powdery emitting member for applying radiation to a target portion in a cavity of a living body; and a thin-walled, flexible tube accommodating the irradiation member.
Still further, the present invention provides a radiation source delivery wire comprising: a flexible operating wire member; and an irradiation member comprising a flexible, deformable medium and a radioactive substance mixed in or carried by the medium, for applying radiation to a target portion in a cavity of a living body.
Still further, the present invention provides a radiation source delivery wire comprising: a flexible operating wire member; and an irradiation member for applying radiation to a target portion in a cavity of a living body, wherein the irradiation member includes a connected body comprising a plurality of individual radiation sources and flexibly bendable connectors connecting the plurality of individual radiation sources substantially on a common axial line, and a joint portion joining a proximal end of the connected body to a distal end of the operating wire member, and the connected body is provided on distal end side relative to the distal end of the operating wire member.
According to another aspect of the present invention, there is provided a catheter assembly for radiation therapy comprising: (a) a radiation source delivery wire of the present invention; and (b) a catheter for radiation therapy comprising a catheter body and an elongated lumen which is provided in the catheter body and through which the radiation source delivery wire can be inserted.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.